Frogs and humans have many comparable body systems, including the respiratory system. Both use their lungs to take in oxygen and expel waste gasses like carbon dioxide. There are differences in the way they breathe, and in the way frogs supplement their oxygen intake through their skin. Understanding the similarities and differences can help you compare and contrast the two.
Explain the similarities between frog lungs and human lungs. Frogs and humans both have a glottis that closes off the trachea when swallowing. They also have a larynx that contains vocal cords, and bronchial tubes that divide into a pair of air sacs called lungs. The lungs are made of elastic tissue and can expand and contract.
Discuss the differences in the mechanics of respiration. Mammals have a sheet of muscle called a diaphragm that is attached to the ribs and the bottom of the lungs. When the diaphragm contracts, it expands the chest cavity and the difference in air pressure sucks air into the lungs. Frogs do not have a diaphragm, and instead they pump air in and out of the lungs by expanding and contracting their throat sac.
Discuss the differences in the skin of frogs and humans. Frogs have a moist, permeable skin, which can transfer gasses such as carbon dioxide and oxygen. Humans have dry skin that is impermeable to gas exchange, so almost all gas exchange takes place in the lungs. This means human lungs must be more efficient than frog lungs.